Approximately 60,000 people worldwide have received cochlear implant devices for their hearing. Following implantation, these individuals not only gain the ability to hear others, but also to hear themselves while they speak (auditory feedback). There is increasing evidence that auditory feedback (AF) is important for speech production; however, much remains to be understood regarding the role of AF, particularly for speech development. The specific aims of this research are to: (1) investigate properties of speech that are modified when cochlear-implanted children speak in the brief absence of AF; (2) compare effects of AF on speech produced by early-implanted (received cochlear implant before 3 years of age) versus late-implanted children (received implant after 5 years of age); and (3) determine the critical time interval between AF deprivation and concomitant changes in speech. These aims are part of a long-range plan to better understand the influences of speech perception on speech production. Ten early- and ten late-implanted children (ages 6-12 years) will read simple phrases in speech processor-ON and -OFF conditions. The following speech properties will be measured using acoustic analysis: vowel formant frequencies, stop consonant voice onset times, fricative spectral moments, syllable-level fundamental frequencies, and word and phrase durations. Analysis of variance with planned comparisons will be used to test the following hypotheses: (1) suprasegmental and segmental properties of speech are modified in the brief absence of AF; (2) early-implanted children show larger speech changes in the absence of AF than late-implanted children; and (3) segmental properties of speech are modified when AF is eliminated for less than a second. The results will have both clinical and theoretical implications in that they: (1) will inform clinicians of the minimal time window over which speech improvements can be expected following implantation; and (2) offer unique means of testing 'internal model'-based theories of sensory feedback during speech production.